* [configs] Remove requires systemd-networkd dep from smfd service
The smf no longer has (never had?) a dependency on systemd-networkd,
and can start and remain operational without systemd-networkd
specifically running.
* [configs] Relax upf dependency on systemd-networkd
The upf relies on systemd-networkd to create the ogstun interface, but
does not communicate with it at runtime. It currently has a "Requires"
dependency specified, which means that the upf will be stopped if
systemd-networkd is ever stopped. Since the upf doesn't actually care
if systemd-networkd is later stopped after ogstun is created, it can
use the weaker "Wants" dependency type, which allows it to keep
running even if systemd-networkd were to be stopped.
Regardless, since it does rely on systemd-networkd specifically to
create the ogstun interface, it should sequence itself "After"
systemd-networkd has been started.
Since the true dependency is ogstun, not systemd-networkd, a cleaner
approach would depend on the specific tunnel device being
available. Systemd exposes this information via device units, but I'm
not sure if they are always consistently named across platforms.
* [configs] Do not require ogstun for system online
Systemd-networkd will wait for all managed interfaces to be configured
before determining the system is online. Since the ogstun and upf are
more logically an application rather than a system networking service,
don't wait for them to be configured by default.
This breaks the circular dependency between the userspace cellular
core network services and the system's network, which will allow the
cellular core network services to sequence themselves cleanly after
the system's network is up and configured.
* [configs] Sequence network-dependent units after network-online
Since open5gs targets platforms with both ifupdown (debian) and
systemd-networkd (Ubuntu) as core networking providers, this commit
sequences network-dependent core network components after the generic
network-online.target instead of one of the specific provider
targets. This allows the core network to operate correctly with both
systemd-networkd and ifupdown (networking), and fixes the issue
observed in https://github.com/open5gs/open5gs/issues/826 where some
platforms may fail to start cleanly.
Matthew Johnson
Sukchan Lee